MUSCLE SCIENCE: Muscles May Preserve A Shortcut To Restore Lost Strength. “Muscle physiology lore has long held that it is easier to regain muscle mass in once-fit muscles than build it anew, especially as we age. But scientists haven’t been able to pin down how that would actually work. A growing body of research reviewed Friday in the journal Frontiers in Physiology suggests that muscle nuclei — the factories that power new muscle growth — may be the answer. Rather than dying as muscles lose mass, nuclei added during muscle growth persist and could give older muscles an edge in regaining fitness later on, new research suggests.”